What used to be labelled as "Tax Matters Partner" is now called the "Partnership Representative".

You need to do some research on this new designation so you understand how this works and the  responsibility that this individual has.  This individual does not have to be a member, BUT will receive all correspondence from the IRS AND this individual has sole authority to make decisions on behalf of the partnership.

For starters, read the 1065 instructions describing this role and who is eligible.

The correspondence you received is most likely a generic letter and just uses the terminology of member since it is an LLC.  Regardless of whether they are a member or not, this individual will receive all correspondence as noted previously.